Zircon U-Pb Geochronology Constrains Continental Expression of Great Meteor Hotspot Magmatism

Abstract

The New England-Québec Igneous Province is considered to be a continental expression of Great Meteor Hotspot magmatism, though other geodynamic scenarios have been suggested. Existing geochronologic data lack the needed accuracy and precision to permit tests of potential causal mechanisms. We provide zircon U-Pb ages for four igneous centers and a suite of plate reconstructions and show that the duration between magmatism in each branch of this province is ca. 3–6 Myr shorter and ca. 10 Myr older than predicted if the spatial-temporal distribution of magmatism conformed to a well-defined age progression. However, in addition to uncertainties in plate reconstructions, variable regional crustal thickness or lithospheric topography likely played a role in mediating the rates of melt transport to emplacement depth and we therefore cannot reject the hotspot hypothesis. Our results place the best-available chronological constraints on continental magmatism associated with one of the oldest and longest-lived hotspots. © 2021. American Geophysical Union. All Rights Reserved.